1. Field of the Invention
The present invention relates to an ink jet recording head and method for manufacturing the same. More particularly, the invention relates to an ink jet recording head for which the water repellency treatment for its discharging port surface is improved, and method for manufacturing the same.
2. Related Background Art
The water repellent film for an ink jet recording head has hitherto been formed by transferring the fluoric copolymer film which has cyclic structure in its principal chain, by coating with absorbent, or formed by spray coating. FIGS. 4 and 5 are views showing the method of formation of the conventional water repellent film for an ink jet recording head. In the conventional technique, the water repellent film formation method is roughly divided into two depending on the difference in head fabrication processes, that is, the two types: one wherein the water repellent film is formed subsequent to the formation of discharging ports such as shown in FIG. 4, and the other wherein subsequent to the formation of water repellent film such as shown in FIG. 5, the discharging ports are formed.
An ink jet recording head 100 shown in FIG. 4A is formed in such a manner that on an ink jet substrate 101 where exothermic resistive elements and others are incorporated, ink passages 102 are formed, a ceiling plate 103 is adhesively bonded, a discharging port surface 105 is cut, and then discharging ports 104 are formed.
To such an ink jet recording head 100, a water repellent film 107 adhering to silicone rubber 106 is transferred. After that, it is hardened by heating (FIG. 4B). The water repellent film is formed by coating a water repellent solvent over the silicon rubber 106 by means of spin coat.
Thus, an ink jet recording head coated with the water repellent solvent 107 is completed (FIG. 4C).
For an ink jet recording head 100 shown in FIG. 5A, the ink passages are patterned by means of positive resist in order to form the ink passages in the ink jet substrate 101 where exothermic resistive elements and others are incorporated, and then molding resin is poured to form the ceiling plate 103. After that, this is cut to form the discharging port surface 105. To such an ink jet recording head 100, the water repellent solvent which has been absorbed into the absorbent 109 is transferred. Then, it is hardened by heating (FIG. 5B). In order to cause the water repellent solvent to adhere to the absorbent 109, the absorbent is immersed in the original liquid of the water repellent solvent or its diluted liquid to allow it to absorb the water repellent solvent. Then, the positive resist 108 is removed by application of aceton. Thus, when the water repellent film on the discharging port portion is given a pressurized cleaning, the ink passages 102 are formed, and an ink jet recording head coated with the water repellent film 107 is completed (FIG. 5C).
There has also been an ink jet recording head which is fabricated in such a manner that the water repellent solvent absorbed into the absorbent 109 is transferred to the discharging port surface of a grooved ceiling plate formed integrally with a liquid chamber, liquid passages, and an orifice surface, and then after hardened by heating, the grooved ceiling plate is machined by means of excimer laser drilling to be integrated with the substrate 101.
However, with the conventional examples described above, it is difficult to coat the water repellent solvent evenly, leading to the lowered reliability of the water repellency of the ink jet recording head due to such an unevenness of the water repellent solvent thus coated. Also, according to the above-mentioned examples, the adhesiveness between the water repellent solvent and the ink jet recording head is not strong enough. For example, therefore, the repeated cleaning processes performed by a blade cause the water repellent film to be peeled off. As a result, the ink ejection condition of the ink jet recording head is degraded in some cases. Thus, the reliability of the water repellent film is lowered.